 "use strict";
function User() {}
User.prototype.getName = function() {
  return this.name;
};

function Stu(name) {
  this.name = name;
}
Stu.prototype = new User();
const lisi = new Stu("李四");

console.log(lisi.__proto__);
console.log(lisi.getName());

console.log(lisi instanceof Stu)
console.log(lisi instanceof User)
